The establishment of a national gravity standard based on international metrological standards is a high priority for the Estonian geodetic, geophysical, and metrological community. With the presently available gravimetric instruments and models, geoscientific research at the level of \(10^{-9}\) g is possible and requires a homogeneous performance of the definition of gravity standards and of measurements of gravity values at the regional to global scale. From 1995 to 2017, five absolute gravimetric measurement campaigns have been carried out to determine the absolute value of gravity acceleration at all of the seven Estonian gravity network points by deploying JILAg, FG5, and FG5X gravimeters. In this study, the absolute gravity (AG) data were collected and reprocessed to unify the corrections due to local vertical gravity gradient, the self-attraction, and diffraction of the absolute gravimeter. The full set of gravity observations was used to estimate the rates of secular gravity change on the periphery of the Fennoscandian postglacial rebound area, which is continuously deforming due to the glacial isostatic adjustment (GIA). The observed gravity rates, which have been estimated using a linear regression model, differ from the gravity rates that are derived from the vertical velocities of the continuous Global Navigation Satellite System (GNSS) stations and the land uplift model NKG2016LU of the Nordic Commission of Geodesy (NKG) for northern Europe. These differences could be the effect of an insufficient amount of data, seasonal, and inter-annual variation in the hydrology on the observed gravity rates, and the offsets of gravimeters. The discrepancies, nevertheless, are within the uncertainties of observed and derived gravity rates. Similarly, an estimated slope of a linear relation between observed gravity rates and vertical velocities is consistent with a GIA model prediction. The effect of possible offsets of gravimeters on Estonian AG data was corrected, based on the results of international comparisons of absolute gravimeters, as well as the regional analysis of Finnish AG data. The linear regression with corrected data did not improve the fit with the rates that were based on vertical velocities. Further, the linear relation between observed gravity and uplift rates deviated more from the GIA prediction. Therefore, our results did not confirm the positive effect of gravimeter offset correction. However, in order to potentially obtain conclusions that are more solid, the absolute gravity measurements should be continued in Estonia to combine longer and denser gravity time series with the modelling of environmental effects (e.g. regional hydrology, the loading of Baltic Sea). This would allow to improve the accuracy of the national gravity frame and observed gravity rates which, in turn, would support the establishment and extension of the International Gravity Reference Frame (IGRF) in the Nordic–Baltic region by following the internationally agreed rules and recommendations of the new global gravity standard.

建立基于国际计量标准的国家重力标准是爱沙尼亚大地测量、地球物理和计量界的重中之重。使用目前可用的重力仪器和模型，地球科学研究在\(10^{-9}\) g是可能的，并且需要在区域到全球范围内对重力标准的定义和重力值的测量进行统一的执行。从 1995 年到 2017 年，通过部署 JILAg、FG5 和 FG5X 重力仪，开展了五次绝对重力测量活动，以确定爱沙尼亚重力网络所有七个点的重力加速度绝对值。在这项研究中，收集和重新处理绝对重力 (AG) 数据以统一由于局部垂直重力梯度、自吸引和绝对重力仪衍射引起的校正。全套重力观测被用来估计芬诺斯坎德冰川后回弹区外围的长期重力变化率，该区由于冰川均衡调整（GIA）而不断变形。使用线性回归模型估计的观测重力率不同于从连续全球导航卫星系统 (GNSS) 站的垂直速度和北欧大地测量委员会的陆地隆起模型 NKG2016LU 得出的重力率(NKG) 北欧。这些差异可能是数据量不足、水文的季节性和年际变化对观测到的重力速率和重力计偏移的影响。然而，这些差异在观测和推导的重力速率的不确定性范围内。类似地，观测到的重力速率和垂直速度之间线性关系的估计斜率与 GIA 模型预测一致。纠正了重力仪可能偏移对爱沙尼亚 AG 数据的影响，基于绝对重力仪的国际比较结果，以及芬兰 AG 数据的区域分析。校正数据的线性回归并没有改善与基于垂直速度的速率的拟合。此外，观测到的重力和隆升率之间的线性关系与 GIA 预测的偏差更大。因此，我们的结果并未证实重力计偏移校正的积极影响。然而，为了有可能获得更可靠的结论，爱沙尼亚应继续进行绝对重力测量，将更长、更密集的重力时间序列与环境影响建模（例如区域水文、波罗的海的负荷）结合起来。这将允许提高国家重力框架和观测重力率的准确性，反过来，